This is a very interesting thread! I am inclined along "mad scientist" lines myself; I'd like to try some of these experiments and see how they turn out for me. Has anyone tried making a cofee liqueur by doing an etanol extraction, then adding some strong water-extracted (espresso) and diluting and sweetening the end product?

Wonderful cup of coffee that his reminiscent of cafe au lait with an overlay of gently roasted coffee grounds. Aroma was quite fascinating - that's just with Eight o Clock Colombia. I will be trying it again at some point with a Uganda, Ethiopia or some other of the African varietals.

I still have a sample of it - after a week it remains emulsified. The only thing that's been successful at separating SOME of it is adding 2ml of the coffee emulsification to 2ml of ethanol (75.5%), agitating, then adding 2ml of distilled water after 3 minutes.

Usually, this is a quick makeshift test for presence of lipids. It is supposed to produce a floating layer of cloudy solution as the ethanol (an organic solvent) dissolves the lipids. Adding the distilled water causes the alcohol dissolved lipids to come out of solution.

However, all this did for the emulsion sample is create a less-cloudy solution with some HEAVIER gunk that has settled somewhere near the bottom of the tube.

I'll give it a spin when I get a chance, but it's been pretty.... interesting.

OK, I tried the OP's thing #2 process and got similar results. I should note that my blender did not pulverise the coffee as finely as the OP's seemed to, however. Also, I filtered the liquid through a paper towel placed in a conical sieve, not an aeropress. After filtration I heated some of the coffee up to about 90 Celsius (in a microwave)

Observations - Cold- Appearance of filtrate was tan, almost opaque liquid like a filter coffee with a dash of skim milk- There were no fine particles visible- Aroma was sweet and fresh- Taste was relatively normal, but seemed slightly more bitter, astringent and woody on the back palate than normal- After 30 mins there were signs of slight oil separation, the liquid was slightly darker and less opaque and some dark sediment had appeared- The oil layer was barely visible and did not have any opacity

Observations - Hot- Coffee immediately looked darker and less opaque than the cold sample, with a developing thin oily film on the surface- As the coffee cooled the film remained and became white and broken in appearance- The cooled hot sample remained significantly darker, clearer and with a much more pronounced oil/wax layer than the cold sample

Hypothesis- The coffee contains high melting point fats (waxes?) that are solid at room temp- The high shear rate of the cold maceration process releases these waxes into suspension and breaks them up into very small particles that turn the liquid opaque and remain suspended (somehow) in the cold liquid- When the liquid is heated to above the melting point of the waxes, they separate out (somehow) and float to the top- Due to the lower shear rate and/or coarser filter medium than the OP's process, the liquid showed sedimentation and produced a less stable emulsion in the cold sample

Possible further tests- Repeat with variations using fine ground coffee produced in coffee grinder- In one variation use same blending process as above- In second variation leave blender off but gently agitate the mix with a stirrer

If my hypothesis is correct then the first variation would be more similar to the OP's results, and the second variation would produce a clearer liquid with a rapidly forming liquid oil layer with little or no waxy component. Further variations could be to repeat the above using a finer filter medium closer to the OP's process. I would expect the main difference here to be removal of the sedimenting fines

Why heating releases the waxes seems unclear. Perhaps the waxes remain bound to insoluble solids, and are only free to escape once they are heated and liquefied

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